Micro cantilever style contact pin structure for wafer probing

Abstract

The present invention is to provide a micro cantilever-type probe disposed on a probe card, having such appropriate elasticity and mechanical strength that the probe would recover its unforced shape after deformation during an inspection and maintain its original shape even after three hundred thousand uses. The present invention provides a probe card which has an electrically insulated substrate fixed on a circuit board; a plurality of elastic probes with a sharpened end fixed on the insulated substrate; and wiring formed on the probe, the insulated substrate and the circuit board. The inventive probe is manufactured by patterning a substrate using photolithography and etching a portion except a pattern-defined portion. The probe is coated by metal layer(s).

What is claimed is:  
     
       1. A probe card for measuring electrical characteristics of a device by electrically coupling probes to pads of said device, said probe card comprising: 
       an electrically insulated substrate fixed on a circuit board;  
       a plurality of probes fixed on said electrically insulated substrate, each having a base, an elastic cantilever, and a pointed end, such that said insulated substrate restricts an elastic micro movement of said elastic micro cantilever;  
       electrical wiring pattern formed on said probes and said insulated substrate; and  
       an electrically conducting layer plated on said electrical wiring pattern,  
       wherein said base, said elastic micro cantilever, and said pointed end of each of said probes are integrally made of single crystal silicon and manufactured by a pattern-defining photolithography that etches away the material except a pattern-defined portion.  
     
     
       2. A probe card according to  claim 1 , wherein said single crystal silicon is (110)-oriented single crystal silicon. 
     
     
       3. A probe card according to  claim 2 , wherein said probes are vertically etched using KOH, TMAH, EDP wet etchant, which has anisotropic etch characteristics. 
     
     
       4. A probe card according to  claim 1  or  2 , wherein said electrically insulating substrate is made of glass or ceramic. 
     
     
       5. A probe card according to  claim 1 , wherein said probes are vertically etched by deep silicon dry etch on a (111)-oriented single crystal silicon. 
     
     
       6. A probe card according to  claim 1 , wherein impurities are introduced into said probes by ion implantation or thermal diffusion to enhance an electrical conductivity of said probes. 
     
     
       7. A probe card according to  claim 1 , wherein said probes are formed by a series of pattern-defining photolithographic and etching processes that etch away unwanted portions from the single crystal silicon. 
     
     
       8. A probe card according to  claim 1 , wherein said electrically conducting layer is plated using electroplating or electroless plating of one or more of metal layer(s) such as copper, platinum, palladium, gold, tungsten, nickel, chrome, nickel chrome alloy. 
     
     
       9. A probe card according to  claim 1 , wherein said probes are fixed on said electrically insulating substrate by using fusion bonding or anodic bonding. 
     
     
       10. A probe card according to  claim 1 , wherein said electrical wiring pattern is created by sputtering, chemical vapor deposition, or evaporation of a electrically conducting material and etching or lifting-off. 
     
     
       11. A probe card according to  claim 10 , wherein, when said lifting-off is used, a sacrificial layer is deposited on the electrically-insulating substrate before said plurality of probes are fixed on said insulated substrate. 
     
     
       12. A probe card according to  claim 10 , wherein said sacrificial layer for said liftoff is made of Al, Ti, Cu, Cr or oxides like as Al 2 O 3 , SiO 2 , TiO 2 . 
     
     
       13. A probe card according to  claim 10 , wherein said photolithography is done by spray coating on a surface of said probe for conformal step coverage of photo resist. 
     
     
       14. A probe card according to  claim 1 , wherein said probes are structurally and electrically separated from one another. 
     
     
       15. A probe card according to  claim 1 , wherein said pointed end of each of said probes is plated with tungsten or tungsten silicide. 
     
     
       16. A probe card according to  claim 1 , wherein said electrical wiring is connected to the said circuit board by wire bonding method. 
     
     
       17. A probe card according to  claim 1 , wherein said electrical wiring is connected to the said circuit board by forming one or plurality of hole(s) in the said insulated substrate and filling the hole with electrically conducting material. 
     
     
       18. A probe card according to  claim 1 , wherein said insulated substrate is cut into desired shape by UV laser, excimer laser, dicing saw, ultrasonic cutter and/or EDM (electrochemical discharge machining). 
     
     
       19. A method for manufacturing probe needles, said method comprising: 
       providing a monolithic single crystal silicon;  
       forming probe needles by defining a pattern on said monolithic single crystal silicon by photolithography and etching away undefined portions of said monolithic single crystal silicon;  
       forming a thin metal layer by sputtering a first metal on the surface of said probe needles; and  
       forming a thicker metal layer by plating a second metal on said thin metal layer,  
       wherein said probe needles each comprises a base, an elastic cantilever, and a pointed end.  
     
     
       20. A method according to  claim 19 , said method further comprising: 
       forming a sacrificial layer by sputtering third metal on a substrate;  
       etching said sacrificial layer using predetermined photoresist pattern to expose selected areas of said substrate;  
       forming said thin metal layer by sputtering said first metal on said sacrificial layer and on the surface of said probe needle body; and  
       forming a wiring pattern by lift-off process on said thin metal layer.